Cyclopropenes as C3 Building Blocks: Cyclopentenols and Large Rings from 2-Aminobicyclopentane Derivatives via Ring-Enlargement Reactions

Article abstract of DOI:10.1055/s-1989-27401

The readily available methyl 3,3-dimethylcyclopropene-1-carboxylate undergoes <2+2> cycloaddition with enamines to give 2-aminobicyclo<2.1.0>pentane derivatives in moderate to good yields.These compounds are quantitatively transformed into 3-cyclopentenols by treatment with dilute mineral acids.From enamines derived from medium-ring ketones and morpholine, tricyclic adducts are formed, which eliminate morpholine under flash-thermolysis conditions at 600 deg C to give macrocycles containing an E double bond and an allenic system.